The consequences of impact of a small asteroid (less then 100 T in mass) on Mars surface are investigated. The atmospheric braking is found to be unimportant as is the maximal dynamic pressure exerted on the impacting body. In other words, the impactor remains unfragmented untill the impact. The resulting crater size depends on the kinetic energy of the impactor and the lithological properties of the martian surface and shallow crust as well as later atmospheric erosion.